The purpose of this paper is to describe global urban greenhouse gas emissions by region and sector, examine the distribution of emissions through the urban-to-rural gradient, and identify covariates of emission levels for our baseline year, 2000. We use multiple existing spatial databases to identify urban extent, greenhouse gas emissions (CO 2 , N 2 O, CH 4 and SF 6) and covariates of emissions in a "top-down" analysis. The results indicate that urban activities are significant sources of total greenhouse gas emissions (36.8 and 48.6 % of total). The urban energy sector accounts for between 41.5 and 66.3 % of total energy emissions. Significant differences exist in the urban share of greenhouse gas emissions between developed and developing countries as well as among source sectors for geographic regions. The 50 largest urban emitting areas account for 38.8 % of all urban greenhouse gas emissions. We find that greenhouse gas emissions are significantly associated with population size, density, growth rates, and per capita income. Finally, comparison of our results to "bottom-up" estimates suggest that this research's data and techniques are best used at the regional and global scales. 1 Introduction Decision makers need baseline data, analysis and monitoring of urban greenhouse gas emissions to verify the effectiveness of policy measures. For example, while urban planners take
In this paper the first active surgical robot system (OTTO) in a clinical environment for maxillofacial surgery is presented. The medical application is described from a technical point of view and the requirements for a robot in this specialty are defined. The paper describes the system architecture of the robotics environment and the need for research and development. The robot's hardware is based o n a delta-kinematics robot system. At the current state of development, the robot can be used for inserting non-flexible catheters and for i mplanting bone fixtures in the skull.
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