The transportation industry is an essential sector for carbon emissions mitigation. This paper firstly used the LMDI (Logarithmic Mean Divisia Index) decomposition method to establish factors decomposition model on China's transportation carbon emission. Then, a quantitative analysis was performed to study the factors influencing China's transportation carbon emissions from 1991 to 2008, which are identified as transportation energy efficiency, transportation structure and transportation development. The results showed that: (1) The impact of transportation development on transportation carbon emissions showed pulling function. Its contribution value to carbon emissions remained at high growth since 1991 and showed an exponential growth trend. (2) The impact of transportation structure on transportation carbon emissions showed promoting function in general, but its role in promoting carbon emissions decreased year by year. And with the continuous optimization of transportation structure, the promoting effect decreased gradually and showed the inversed "U" trend. (3) The impact of transportation energy efficiency on transportation carbon emissions showed a function of inhibition before pulling. In order to predict the potential of carbon emission reduction, three scenarios were set. Analysis of the scenarios showed that if greater intensity emission reduction measures are taken, the carbon emissions will reduce by 31.01 million tons by 2015 and by 48.81 million tons by 2020.
Generally, multicountry papers receive more citations than single‐country ones. In this contribution, we examine if this rule also applies to American scientists publishing in highly visible interdisciplinary journals. Concretely, we compare the citations received by American scientists in Nature, Science, and the Proceedings of the National Academy of Sciences of the United States of America (PNAS). It is shown that, statistically, American scientists publishing in Nature and Science do not benefit from international collaboration. This statement also holds for communicated submissions, but not for direct and for contributed submissions, to PNAS.
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