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This paper studies the volatility of commodity prices on the basis of a large dataset of monthly prices observed in international trade data from the United States over the period 2002 to 2011. The conventional wisdom in academia and policy circles is that primary commodity prices are more volatile than those of manufactured products, even though most of the existing evidence does not actually attempt to measure the volatility of prices of individual goods or commodities. Rather the literature tends to focus on trends in the evolution and volatility of ratios of price indexes composed of multi

AbstractThis paper presents a new perspective for understanding the land sale behaviour of local governments in China, focusing on the 'institutional trinity' of the land market; namely, state ownership, economic performance‐based political promotion and the unbalanced fiscal structure. The paper argues that the main motivations of local government to sell land are to promote industrial growth and to enhance government fiscal capacity. These two hypotheses are tested using prefecture‐level data covering approximately 330 municipalities during the period of 1999–2007. The paper finds that industrial output and fiscal expenditure increase by approximately 1.8% and 1.0%, respectively, if the area of land sale doubles. Evidence also shows that land sale promotes industrial growth by boosting fixed asset investment and foreign direct investment. Interestingly, the paper also finds that the land‐sale strategy of local governments is more effective in the eastern provinces than in other regions.

Emissions of the fine particulate matters (diameter of 2.5 μm or less) caused by both the primary particle emissions and the precursor emission sources such as sulfur dioxide and nitrogen oxides, have contributed significantly to poor urban air quality in China, and have attracted tremendous public attention over the past few years. This study provides an interdisciplinary study to investigate the key contributors driving air pollution emissions changes in China from 1997 to 2012, by applying the Logarithmic Mean Divisia Index method. The decomposition results are presented in both multiplicative and additive approaches to show the relative and absolute contribution of each factor in affecting emission changes. Changes in total particulate matter emissions are attributed to variations in primary particle, sulfur dioxide and nitrogen oxides emissions. It is manifested that the economic growth effect and energy intensity effect have always been the two key drivers in affecting the changes in air pollutant emissions over the period. The effects of emission efficiency, production structure and population growth contribute less significantly to overall emission changes, and the impacts of different factors vary among different pollutants. Since current strategies and policies in combatting particulate matter emissions are inefficient, this paper provides a guideline for the Chinese Government to deal with the air pollution problem for sustainable development in China.

Clostridium perfringens (CP) is the etiologic agent of necrotic enteritis (NE) in broiler chickens that is responsible for massive economic losses in the poultry industry in response to voluntary reduction and withdrawal of antibiotic growth promoters. large variations exist in the CP isolates in inducing intestinal NE lesions. However, limited information is available on CP isolate genetics in inducing NE with other predisposing factors. This study investigated the ability of five CP isolates from different sources to influence NE pathogenesis by using an Eimeria maxima (EM) coinfection NE model: Str.13 (from soil), LLY_N11 (healthy chicken intestine), SM101 (food poisoning), Del1 (net(+)tpeL(-)) and LLY_Tpel17 (netB(+)tpeL(+)) for NE-afflicted chickens. The 2-wk-old broiler chickens were preinfected with EM (5 X 10(3) oocysts) followed by CP infection (around 1 X 10(9) colony-forming units per chicken). The group of the LLY_Tpel17 isolate with EM coinfection had 25% mortality. No mortality was observed in the groups infected with EM alone, all CP alone, or dual infections of EM/other CP isolates. In this model of EM/CP coinfections, the relative percentages of body weight gain showed statistically significant decreases in all EM/CP groups except the EM/SM101 group when compared with the sham control group. Evident gut lesions were only observed in the three groups of EM/LLY_N11, EM/Del1, and EM/LLY_Tpel17, all of which possessed an essential NE pathogenesis locus in their genomes. Our studies indicate that LLY_Tpel17 is highly pathogenic to induce severe gut lesions and would be a good CP challenge strain for studies investigating pathogenesis and evaluating the protection efficacy for antibiotic alternative approaches. ; Agricultural Research Service, USDAUnited States Department of Agriculture (USDA)USDA Agricultural Research Service ; This work was supported by the funds from Agricultural Research Service, USDA. The authors declare that they have no competing interests. ; Public domain authored by a U.S. government employee