Natural resources and development: The gold sector in Mali

Resource-rich countries do not necessarily perform well, especially developing countries. A debate has developed since the 1990s about a “resource curse” hypothesis, which threaten to impede the resource-rich countries in taking advantage of their natural endowments. In Mali, a less-developed country, gold export has substantially increased since the 1990s. In this paper we show that widespread analyses, such as those of the Dutch disease and the quality of institutions, are not sufficient to understand what is at stake in Mali, and that the mining sector has proved to be neither a blessing nor a curse, at least until the present. Gold mining has brought budget revenues but induced few spillovers. As gold mining has now come to maturity, the die is probably cast.     

Investor demand and spot commodity prices

The on-going debate over the influence of investor demand on spot commodity prices largely attempts to assess this influence by measuring the growth in investor demand in recent years. Given the serious data problems that plague such analyses, this article pursues another approach in the hope of providing useful insights into the impact of investor demand on spot commodity prices. It focuses on the mechanisms by which investor demand affects spot prices, and in particular on two questions. First, how does an increase in investor demand on the futures markets affect the spot market and spot price? Second, when investor demand is increasing and pushing a commodity's price up, do physical stocks of the commodity also have to be rising, as economists and others widely assume?On the first question, the article concludes that a surge in investor demand raising prices on the futures markets will have a direct and comparable effect on the spot market prices when these markets are in strong contango. However, when markets are in weak contango or backwardation, price movements in the futures markets have a much looser effect on spot prices. As a result, changes in investor demand on the futures markets may have little or no influence on spot prices in the absence of a strong contango. Instead, changes in fundamentals (that is, producer supply and consumer demand) and possibly changes in investor demand taking place directly on the spot market largely determine the spot price at such times.On the second question, the article shows that investor demand can be pushing up a commodity's price even when investor stocks are falling, despite the widespread presumption to the contrary.     

珠江三角洲四种森林类型土壤CO_2通量特征研究

采用开路式土壤CO2通量测量系统Li-8100＆Li-8150对珠江三角洲地区尾叶桉（Eucalyptus urophylla）人工林、乡土树种恢复林、针阔叶混交林和常绿阔叶林4种林型的土壤CO2通量进行了观测。结果表明：4种森林类型年均土壤CO2通量为尾叶桉人工林（3.35μmol.m-2.s-1）〉针阔叶混交林（2.66μmol.m-2.s-1）〉乡土树种恢复林（2.09μmol.m-2.s-1）〉常绿阔叶林（1.86μmol.m-2.s-1）;旱季土壤CO2通量明显小于雨季。前3种森林类型凋落物呼吸处理表明,旱季对照组土壤CO2通量均小于相应的去除凋落物组、雨季则相反,全年的对比结果显示,3种森林类型的凋落物呼吸贡献分别达到1.3%、7.1%和10.8%。土壤CO2通量与10 cm土壤温度呈显著指数相关,且土壤CO2通量温度敏感指数表现为针阔叶混交林Q10最大（3.49）,尾叶桉人工林Q10最小（1.95）。     

Q345钢在不同pH值人工海水中的电偶腐蚀行为研究

目的 研究不同pH值的人工海水环境中电偶腐蚀对金属的影响。方法 利用自行设计的可拆卸电极,采用浸泡法和电化学方法,结合宏观和微观腐蚀形貌,对Q345钢在不同pH人工海水中的电偶腐蚀行为进行分析。结果 在浸泡初期,不同pH值海水环境中电连接电极间的电位差相差较小,不易发生电偶腐蚀;浸泡至14 d,电极间的电位差相差较大,这表明不同电连接电极之间发生明显的电偶腐蚀。与自腐蚀相比,pH为7.50和8.40的电偶腐蚀的腐蚀电位较大,腐蚀电流密度较小,腐蚀产物膜电阻Rp较大,说明在pH值为7.50和8.40时,电连接电极间的腐蚀以自腐蚀为主。在pH值为7.80和8.70时,电连接电极间发生明显的电偶腐蚀。自腐蚀电极表面的腐蚀产物较少,锈层结构疏松。电偶腐蚀中,在pH为7.50和8.40的电极表面的腐蚀产物较少,锈层结构致密;pH为7.80和8.70的电极表面的腐蚀产物较多,锈层结构比较疏松。结论 通过研究2种腐蚀行为的差异,分析pH值的不同对电偶腐蚀的影响,为海洋环境金属材料的腐蚀防护提供数据支持。     

2013~2019年臭氧污染导致的江苏稻麦产量损失评估

基于2013~2019年江苏省115个监测站点的逐时臭氧观测数据和97个县级行政区的农作物年产量,利用AOT40的暴露响应关系,结合空间分析等方法,评估了臭氧污染导致的冬小麦和水稻两种农作物的产量损失.结果表明,2013~2019年,冬小麦和水稻的AOT40分别为（2.76~17.05）×10^-6h和（0.15~31.69）×10^-6,分别在2018年和2016年达到峰值.苏南地区水稻生长期的AOT40高值分布较多,苏北地区近3年两种农作物生长期的AOT40都有明显增势.2013~2019年,冬小麦年相对产量损失为17.7%~31.0%,年绝对产量损失达（1.94~3.75）×10⁶t.年产量损失最高的地级市是盐城和徐州,损失最低的是南京和无锡.2013~2019年,水稻年相对产量损失为8.6%~15.6%,绝对产量损失为（3.03~6.04）×10⁶t.年产量损失最高的地级市是盐城和淮安,损失最低的是无锡和常州.江苏省每年由于臭氧污染导致的农作物产量损失约相当于5000多万人一年的粮食消费量,臭氧污染对粮食生产安全造成了较为严重的威胁,应当采取有效的政策和措施控制臭氧污染,保证粮食生产稳定.     

三种除锈方式对Q235钢表面涂层耐蚀性能的影响

目的对比研究3种不同除锈方式(打磨除锈、先除锈后磷化、除锈-磷化一体化)处理Q235钢表面后,对涂层的耐腐蚀性能的影响。方法在3种除锈方式处理后的Q235钢表面喷涂石墨烯环氧富锌底漆,测试涂层的附着力,通过中性盐雾试验测试涂层的耐腐蚀性能。结果Q235钢经过除锈-磷化一体化处理后,表面性能变优,涂层附着力达到13.6MPa,1000h中性盐雾试验后,涂层不起泡、不脱落,腐蚀程度小。结论除锈-磷化处理Q235钢表面可有效提高防腐涂层的耐蚀性能,与先除锈后磷化相比,简化了工艺过程。     

Tying enforcement to prices in emissions markets: An experimental evaluation

We present results from laboratory emissions permit markets designed to investigate the transmission of abatement cost risk to firms' compliance behavior and regulatory enforcement strategies. With a fixed expected marginal penalty, abatement cost shocks produced significant violations and emissions volatility as predicted. Tying the monitoring probability to average permit prices effectively eliminated noncompliance, but transmitted abatement cost risk to monitoring effort. Tying the penalty to average prices reduced violations, but did not eliminate them. Some individuals in these treatments sold permits at low prices, presumably in an attempt to weaken enforcement. While tying sanctions directly to prevailing permit prices has theoretical and practical advantages over tying monitoring to prices, our results suggest that tying sanctions to prices may not be as effective as predicted without additional modifications.     

Neighborhood effects in the Brazilian Amazônia: Protected areas and deforestation

This article investigates whether protected areas are efficient instruments against deforestation in the Brazilian Amazônia. A Dynamic Spatial Durbin Model taking into account both the location bias and the spatial spillover effects between municipalities allows to assess the impact of the different types of protected areas (integral protected areas, sustainable protected areas and indigenous lands) on deforestation. We show that deforestation decisions are strategic complements. The econometric results differ according to the type of protected area. It is shown that: i) integral protected areas and indigenous lands allow for reducing deforestation; ii) sustainable use areas do not help to reduce deforestation; and iii) the spillover effects generated by integral protected areas and indigenous lands lead a reduction in deforestation in their vicinity. A 10% increase in the surface area of integral protected areas (indigenous lands) allows an estimated 9.32 sq. km (10.08 sq. km) of avoided deforestation.     

Input–output analysis in an oil-rich economy: The case of Azerbaijan

This paper aims to provide empirical research to identify the linkages between final demand–total output, final demand–total supply, value-added ratios and prices, and also to analyze total factor productivity growth using input–output framework for 25 sectors. Studying the input–output tables for 2001 and 2006, the research estimates impact and response multipliers of non-oil sectors, as well as non-oil trading sectors. The results are important from the view of development of non-oil trading sectors and diversification of the economy in order to avoid the “resource curse”.     

Human serum paraoxonase gene polymorphisms and association with chronic symptoms of pesticide toxicity in Indian farmers

The association between PON1 (serum paraoxonase) genotype and symptoms of pesticide toxicity was examined in a total of 268 farm workers in Andhra Pradesh, India. Approximately 140 of the farm workers who did not report at least two of the symptoms of chronic toxicity, such as abdominal pain, nausea, dizziness, headache, drowsiness, fatigue, tremors of fingers, numbness, or limb weakness were categorized as controls. The remaining 128 farmers showed 2 or more of the above symptoms. All the farm workers were genotyped for polymorphisms of PON1 gene at amino acid positions 55 (exon 3) and 192 (exon 6). A decrease in the percentage of high-activity genotypes at both L55M and Q192R was observed in the farm workers reporting symptoms of pesticide toxicity. When combined genotype distribution at both exons was analyzed, a marked increase in the percentage of low-activity genotypes LLQQ, LMQQ, MMQQ, and MMQR was also observed in symptomatic farmers compared to controls. Age, working years, smoking, duration of exposure, and alcoholism were not statistically significant when compared to symptoms of chronic toxicity. Our findings suggest that L55M and Q192R gene polymorphisms influence the variable susceptibility of farmers to pesticide; and thus may be considered a useful biomarker of genetic susceptibility in assessing an individual's risk of pesticide exposures.