Is the convenience yield a good indicator of a commodity's supply risk?

A strong increase in the demand for some commodities over the last decade will have a major impact on their future supply situation. Of increasing importance, therefore, is an assessment of a commodity's criticality, and especially its supply risk, by appropriate indicators. The literature has proposed numerous indicators of the supply risk. Here, we use the convenience yield of commodity futures as a supply risk indicator to address some of the major shortcomings of existing indicators, especially regarding their predictive power. This paper aims to test the applicability of the convenience yield as an indicator of a commodity's future supply risk. Therefore, we calculate historical convenience yields for 3-, 15-, and 27-month futures contracts for five major industrial metals (aluminum, copper, lead, nickel, and zinc) during the period 1999 to 2011. We compare the convenience yields at the beginning of the contract period to known indicators at maturity to find that the convenience yield has generally predictive power for the static stock lifetime (i.e., inventory volume/turnover) and future spot prices. Furthermore, we find that, with some restrictions, the convenience yield is an applicable indicator of a commodity's supply risk.     

The Misdiagnosis: Rethinking “Nature-deficit Disorder”

This study examines and critiques “nature-deficit disorder” (NDD), Richard Louv's popular theory of how and why children are alienated from nature. Specifically, I explore NDD within the context of one forest conservation education program that aligns with and operationalizes Louv's message. Underlying Louv's and forest educators' discourses are culturally specific assumptions about human-nature relationships. Both evoke a fall-recovery narrative—that children are separated from nature and must return—and promote science and naming to reconnect. I argue that, in the absence of deeper cultural examination and alternative practices, NDD is a misdiagnosis—a problematic contemporary environmental discourse that can obscure and mistreat the problem. I call on adults to rethink human-nature disconnectedness by returning to the psyche, digging deeper to the problem's cultural roots, and using nontraditional communication practices such as emotional expression and non-naming.     

"有序"开采:北方地区地下水资源利用中两难选择的途径

北方干旱、半干旱地区地下水超采严重，水资源供需矛盾突出。为探索一条地下水合理开发利用的途径．本文提出了“有序”开采的思路：在来来几十年内．政府部门应根据人口，经济发展规划提出地下水资源需求量的控制计划．并给下属各地区下达取水配额。使储存资源的消耗处于有计划和监控范围内。有序开采应分阶段实现：第一阶段应以抑侧超采量的过快增长为目标；第二阶段应以需水总量的下降为目标；第三阶段应实现总需水量低于地下水系统补给资源量，使数十年超采造成的储存资源亏空逐年得以偿还。“有序”开采应注意三点：①超采必须限制在有限时间内；②开采活动应在政府的严格控制之下。任何超过计划配额的取水行为都是不允许的；③开采量和总需水量的下降，必须以节水为前提。发达国家的需水量变化经历证明。通过“有序”开采实现北方地区地下水可持续利用是可行的．     

Prenatal Diagnosis of congenital disorder of glycosylation type Ia (CDG-Ia) by cordocentesis and transferrin isoelectric focussing of serum of a 27-week fetus with non-immune hydrops

Blood was obtained by cordocentesis from a fetus with non-immune hydrops demonstrated by ultrasound scanning at 27 weeks' gestation. Abnormalities of serum transferrin isoelectric focussing (IEF) were identified, characteristic of a congenital disorder of glycosylation type I (CDG-Ia). A diagnosis of CDG-Ia was confirmed by enzyme analysis of cultured amniocytes. This is the first report of CDG-Ia diagnosed by serum analysis in a fetus. Previous reports have warned that diagnostic abnormalities do not appear in serum until several weeks after birth. The sensitivity of cordocentesis transferrin IEF is unknown but is less than 100% effective because cases have been diagnosed postnatally after normal prenatal or neonatal studies. Enzyme analysis or mutation analysis is required for diagnosis of congenital disorder of glycosylation (CDGs) regardless of whether a diagnostic transferrin pattern is identified prenatally. The analysis of a small sample of serum, from cordocentesis, performed to check for fetal anemia, simplified the investigation, diagnosis, and genetic counselling of a case of non-immune hydrops detected at 27 weeks' gestation. This might be a useful test for other cases in these circumstances, as fetal blood is usually collected to check for anemia. Copyright © 2006 John Wiley & Sons, Ltd.     

Factors affecting the musculoskeletal disorders of workers in the frozen food manufacturing factories in Thailand

The purpose of this research was to study factors affecting musculoskeletal disorders. The sample population of the study was 528 factory workers from the frozen food industry, as well as a controlled group of 255 office workers. The samples were collected during interviews using the Nordic questionnaire to assess musculoskeletal disorders, and to assess the risk by the rapid upper limb assessment and rapid entire body assessment techniques. The findings of the study were that most symptoms were found in the dissecting department, higher than in the controlled group. The details of the symptoms were, accordingly: elbow pain (adjusted odds ratio, 35.1; 95% CI [17.4, 70.9]). Regarding the risk of alcohol drinking, workers were exposed to more risks when alcohol was consumed. It is suggested that workers’ health should be monitored regularly. People who work in a cold environment should be encouraged to wear body protection and to avoid drinking.     

长距离输煤管道储浆罐与石油储罐对比研究

对比研究长距离输煤管道储浆罐与石油储罐搅拌设计特点、罐顶设计特点、消防安全设施特点。经分析可知,长距离输煤管道储浆罐宜选用推进式搅拌器,罐壁上设置导流结构,宜采用固定顶、锥顶,设置简单消防安全设施,宜选用难燃保温材料;石油储罐优先选用旋转喷射式搅拌器,罐内油品进行定期搅拌,采用浮顶,大型的一般选用外浮顶,需设置完善消防安全设施。     

Analysis of posttraumatic stress disorder in children with road traffic injury in Wenzhou,China

Objective: Road traffic accidents are the leading health threat to children and cause significant long-term mental health problems. This study aimed to characterize posttraumatic stress disorder (PTSD) in children suffering from road traffic injuries (RTIs) in Wenzhou, China.

Methods: We conducted a retrospective study of 537 children (aged 1 to 13 years old) with RTIs. The epidemiological features, PTSD incidence, clinical manifestation, and risk factors were analyzed based on a customized PTSD risk factor questionnaire. The outcome factors were also evaluated by means of the logistic regression method.

Results: The PTSD incidence was 24.77% in children with RTIs. The incidence of PTSD was related to the personality, family environment, and family care of the children. It was found that early psychological intervention and reasonable family care from the family might promote physical and mental welfare as well as contribute to the development of more effective treatments to prevent PTSD.

Conclusion: For susceptible children, in addition to dealing with the somatic injury, psychological intervention and family care should be carried out as early as possible.     

A CFD based explosion risk analysis methodology using time varying release rates in dispersion simulations

A full probabilistic Explosion Risk Analysis (ERA) is commonly used to establish overpressure exceedance curves for offshore facilities. This involves modelling a large number of gas dispersion and explosion scenarios. Capturing the time dependant build up and decay of a flammable gas cloud size along with its shape and location are important parameters that can govern the results of an ERA. Dispersion simulations using Computational Fluid Dynamics (CFD) are generally carried out in detailed ERA studies to obtain these pieces of information. However, these dispersion simulations are typically modelled with constant release rates leading to steady state results. The basic assumption used here is that the flammable gas cloud build up rate from these constant release rate dispersion simulations would mimic the actual transient cloud build up rate from a time varying release rate. This assumption does not correctly capture the physical phenomena of transient gas releases and their subsequent dispersion and may lead to very conservative results. This in turn results in potential over design of facilities with implications on time, materials and cost of a project.In the current work, an ERA methodology is proposed that uses time varying release rates as an input in the CFD dispersion simulations to obtain the fully transient flammable gas cloud build-up and decay, while ensuring the total time required to perform the ERA study is also reduced. It was found that the proposed ERA methodology leads to improved accuracy in dispersion results, steeper overpressure exceedance curves and a significant reduction in the Design Accidental Load (DAL) values whilst still maintaining some conservatism and also reducing the total time required to perform an ERA study.     

基于性能参数退化的某弹用O型橡胶密封圈贮存寿命评估

目的研究某弹用O型橡胶密封圈的性能参数退化规律,并准确预测其贮存寿命。方法设计4个不同温度下的恒定应力加速退化试验,记录每个温度下不同时间点的性能退化数据,根据退化参数利用高分子材料性能变化与退化时间关系式及阿伦尼乌斯(Arrhenius)方程,建立O型橡胶密封圈压缩永久变形率与贮存时间的老化动力学方程。结果对照当地各个季节的平均温度值,建立了寿命评估模型,并由此预测了该型密封圈在自然环境贮存条件下的失效寿命在8年左右。结论该寿命评估值比较接近实际测量值,精度良好,可为O型橡胶密封圈在自然贮存条件下的寿命评估提供有价值的参考依据。     

油气储运设施事故风险指数模糊逻辑评估方法

油气储运设施风险是其事故发生概率和事故后果的综合度量,而事故概率和后果的定量评估结果往往是具有不确定性的数据,以确定性风险评估准则为基础的传统风险矩阵法和风险值法显然难以评估油气储运设施风险。为此提出开展油气储运设施事故风险的模糊逻辑推理法,首先,对风险矩阵的概率语言等级和损失语言等级的边界进行定量划分;然后,建立油气储运设施风险矩阵模糊集和模糊逻辑推理规则;最后,通过风险模糊推理运算和模糊风险解模糊化以确定油气储运设施的风险水平。实例应用与分析表明,利用推荐方法可得到较为详尽的风险数据信息,不但风险指数更加清晰,而且其所属风险等级类别也更加明确,评估结果能更好地指导油气储运设施的风险管理。