Suchergebnisse

Parallelism in the download process of large files is an efficient mechanism for distributed systems. In such systems, some peers (clients) exploit the power of parallelism to download blocks of data stored in a distributed way over some other peers (servers). Determining response times in parallel downloading with capacity constraints on both the client downloads and server uploads necessitates understanding the instantaneous shares of the bandwidths of each client/server is devoted to each data transfer flow. In this report, we explore the practical relevance of the hypothesis that flows share the network bandwidth according to the max-min fairness paradigm. We have implemented into a flow-level simulator a version of the algorithm which calculates such a bandwidth allocation, which we have called the ''progressive-filling flow-level algorithm''. We have programmed a similar model over NS2 and compared the empirical distributions resulting from both simulations. Our results indicate that flow-level predictions are very accurate in symmetric networks and good in asymmetric networks. Therefore, PFFLA would be extremely useful to build flow-level simulators and, possibly, to perform probabilistic performance calculations in general P2P networks.

There is a well-known debate about the roles of geography versus institutions in explaining the long-term development of countries. These debates have usually been based on cross-country regressions where questions about parameter heterogeneity, unobserved heterogeneity, and endogeneity cannot easily be controlled for. The innovation of Acemoglu, Johnson and Robinson (2001) was to address this last point by using settler mortality as an instrument for geography-induced endogenous institutions and found that this supported their line of reasoning. We believe there is value-added to consider this debate at the micro level within a country as particularly questions of parameter heterogeneity and unobserved heterogeneity are likely to be smaller than between countries. Moreover, at the micro level it is possible to identify more precise transmission mechanisms from geography via institutions to economic development outcomes. In particular, we examine the determinants of economic development across villages on the Indonesian Island of Sulawesi and find that geography-induced endogenous emergence of land rights is the critical institutional link between geographic conditions and technological change. We therefore highlight and empirically validate a new transmission channel from endogenously generated institutions on economic development. -- Geography ; migration ; land rights ; institutions ; technology adoption ; agricultural development ; Indonesia

This article examines the importance of action-theoretical considerations in European studies. By outlining the notion of "usage" of the European Union, we argue for a more systematically sociological consideration of strategic action in the study of European transformations. The recent turns towards constructivism and comparative political sociology allow analyzing the rationality of political actors without falling in the trap of overly reductionist rational choice assumptions. Concentrating on intentional action helps to reveal the importance of three aspects of the multi-level polity: (1) informal and non-constraining procedures, (2) the effects of ways in which actors move in between the different levels of the European political system, and (3) the ambiguous and often surprising coalitions that come together despite often considerable disagreement over their final goals.

This article examines the importance of action-theoretical considerations in European studies. By outlining the notion of "usage" of the European Union, we argue for a more systematically sociological consideration of strategic action in the study of European transformations. The recent turns towards constructivism and comparative political sociology allow analyzing the rationality of political actors without falling in the trap of overly reductionist rational choice assumptions. Concentrating on intentional action helps to reveal the importance of three aspects of the multi-level polity: (1) informal and non-constraining procedures, (2) the effects of ways in which actors move in between the different levels of the European political system, and (3) the ambiguous and often surprising coalitions that come together despite often considerable disagreement over their final goals.