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We present a self-consistent empirical model for several plasma parameters of a polar coronal hole near solar minimum, derived from observations with the Solar and Heliospheric Observatory Ultraviolet Coronagraph Spectrometer. The model describes the radial distribution of density for electrons, H , and O and the outflow of O are also significantly larger than the corresponding velocities of H . We discuss the constraints and 5ϩ 0 implications on various theoretical models of coronal heating and acceleration.

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ABSTRACT/Methods for evaluating natural areas have evolved in the last couple of decades to assess the importance of natural areas for the purposes of land-use planning, environmental impact assessment, and planning protected areas. Criteria used for evaluation vary and generally fall into three categories: ecological, or abiotic and biotic; cultural; and planning and management. Abiotic and biotic criteria are reviewed here in terms of three questions for each criterion: What is it--what are the definitions used in the ecological and environmental management literature? Why use it--what are the reasons behind its use? How has it been used--what is the state-of-the-art in assessing the criterion? Cultural criteria are discussed more generally in terms of the commonly used frameworks and the concept of significance. Planning and management criteria are generally related to either the need for management action or feasibility of effective management.

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