A \u27whole system\u27 approach to the choice of electoral rules in democratizing countries: Senegal in comparative perspective

Authoritarian incumbents in democratizing countries choose electoral rules to retain power while accommodating opposition demands for increased participation and representation. We clarify the political logic of this institutional choice and its consequences in Senegal by employing a ‘whole system’ approach that emphasizes the intricate but often hidden relationships between elections and the rules governing them at multiple levels — presidential, legislative and local. Success at one level depends on performance at all levels. In the short run, multiple-level electoral reforms preserve the ruling party in power while expanding opportunities for, but also fragmenting, the opposition. In the long run, they encourage splits within the ruling party and help the opposition develop increased ability to coalesce around a single opposition candidate, resulting in the defeat of the authoritarian incumbent and a democratic transfer of power through competitive elections

Efficient Bulk Operations on Dynamic R-Trees

In recent years there has been an upsurge of interest in spatial databases. A major issue is how to manipulate efficiently massive amounts of spatial data stored on disk in multidimensional spatial indexes (data structures). Construction of spatial indexes (bulk loading) has been studied intensively in the database community. The continuous arrival of massive amounts of new data makes it important to update existing indexes (bulk updating) efficiently. In this paper we present a simple, yet efficient, technique for performing bulk update and query operations on multidimensional indexes. We present our technique in terms of the so-called R-tree and its variants, as they have emerged as practically efficient indexing methods for spatial data. Our method uses ideas from the buffer tree lazy buffering technique and fully utilizes the available internal memory and the page size of the operating system. We give a theoretical analysis of our technique, showing that it is efficient both in terms of I/O communication, disk storage, and internal computation time. We also present the results of an extensive set of experiments showing that in practice our approach performs better than the previously best known bulk update methods with respect to update time, and that it produces a better quality index in terms of query performance. One important novel feature of our technique is that in most cases it allows us to perform a batch of updates and queries simultaneously. To be able to do so is essential in environments where queries have to be answered even while the index is being updated and reorganized