Assessing the Uncertainty of Land Based Carbon Sequestration: A Parameter Uncertainty Analysis with a Global Land Use Model

This paper analyzes the effect of uncertainty in several key parameters on the marginal costs of carbon sequestration in forests. These parameters include the land supply elasticity, which governs the conversion of land from agriculture to forests and vice versa; parameters of the forest biomass yield function; parameters of the forest carbon density function; and parameters of the costs functions for accessing inaccessible land. Monte Carlo techniques are thus used to turn the global forest model with no probability (e.g., Sohngen & Mendelsohn, 2003; 2007) into a proper probability model through Latin hypercube sampling. For this paper, we have restricted our analysis to consideration of probability distributions for only two of the parameters described above. Specifically, these are the parameters of the forest biomass yield function and the land supply elasticity. The importance index and the least square linearization are used to determine the relative contribution of input parameters to the model results. Five hundred model runs in one simulation were performed with covariability among the parameters. The Monte Carlo simulations indicated that most of the uncertainty in forest area in developed countries relates to uncertainty in parameters of the biomass function while in developing countries, where deforestation is more important (e.g., Brazil), the simulation showed the parameters of land supply elasticity to have the most important implications for carbon supply. These results are perhaps not too surprising but they do point to the need to empirically estimate land supply elasticities in regions like Brazil, where such estimates are not currently available in the literature. The results also provide information that can be used to estimate uncertainty intervals for carbon sequestration cost functions.Uncertainty Analysis, Global Land Use Model, Carbon Sequestration, Monte Carlo simulations, Resource /Energy Economics and Policy,

Challenging the Non-Native English Speaker Identity in U.S. Higher Education: A Case of International Graduate Students

The present study is grounded in the theoretical understanding of U.S. graduate- level classes as a community of practice and the poststructuralist understanding of language use and identity. In this study, I use a questionnaire and semi- structured interviews to explore how graduate students—both native and non- native English-speaking—perceive their own and others’ participation in class discussions. Also, with a focus on their identity negotiated during their class interactions, I examine possible unequal power relations in graduate classrooms. The results showed that the native students had negative attitudes toward non-native students’ participation, most participants felt that unequal power relations exist in classroom communities, and some non-native students felt marginalized in the classroom. Lastly, some suggestions are presented to bring about equal positioning and harmony in graduate classroom communities

Comparative study between N-body and Fokker-Planck simulations for rotating star clusters: I. Equal-mass system

We have carried out N-body simulations for rotating star clusters with equal mass and compared the results with Fokker-Planck models. These two different approaches are found to produce fairly similar results, although there are some differences with regard to the detailed aspects. We confirmed the acceleration of the core collapse of a cluster due to an initial non-zero angular momentum and found a similar evolutionary trend in the central density and velocity dispersion in both simulations. The degree of acceleration depends on the initial angular momentum. Angular momentum is being lost from the cluster due to the evaporation of stars with a large angular momentum on a relaxation time scale.Comment: 11 pages, 13 eps figures, accepted for the publication of MNRA