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Average incomes of the poorest fifth of society rise proportionately with average incomes. This is a consequence of the strong empirical regularity that the share of income accruing to the bottom quintile does not vary systematically with average income. In this paper we document this empirical regularity in a large sample of 92 countries spanning the past four decades, and show that it holds across regions, time periods, income levels, and growth rates. We next ask whether the factors that explain cross-country differences in growth rates of average incomes have differential effects on the poorest fifth of society. We find that several determinants of growth -- such as good rule of law, openness to international trade, and developed financial markets -- have little systematic effect on the share of income that accrues to the bottom quintile. Consequently these factors benefit the poorest fifth of society as much as everyone else. There is some weak evidence that stabilization from high inflation as well as reductions in the overall size of government not only raise growth but also increase the income share of the poorest fifth in society. Finally we examine several factors commonly thought to disproportionately benefit the poorest in society, but find little evidence of their effects. The absence of robust findings emphasizes that we know relatively little about the broad forces that account for the cross-country and intertemporal variation in the share of income accruing to the poorest fifth of society. _________________________ 1818 H Street N.W., Washington, DC, 20433 (ddollar@worldbank.org, akraay@worldbank.org). We are grateful to Dennis Tao for excellent research assistance. This paper and the accompanying dataset are available at www.worldbank.org/research/gro...

This paper describes a network storage system, called Venti, intended for archival data. In this system, a unique hash of a block's contents acts as the block identifier for read and write operations. This approach enforces a write-once policy, preventing accidental or malicious destruction of data. In addition, duplicate copies of a block can be coalesced, reducing the consumption of storage and simplifying the implementation of clients. Venti is a building block for constructing a variety of storage applications such as logical backup, physical backup, and snapshot file systems.

AspectJ implementations of the GoF design patterns show modularity improvements in 17 of 23 cases. These improvements are manifested in terms of better code locality, reusability, composability, and (un)pluggability. The degree of

We present a primal-dual interior-point algorithm with a filter line-search method for non-linear programming. Local and global convergence properties of this method were analyzed in previous work. Here we provide a comprehensive description of the algorithm, including the feasibility restoration phase for the filter method, second-order corrections, and inertia correction of the KKT matrix. Heuristics are also considered that allow faster performance. This method has been implemented in the IPOPT code, which we demonstrate in a detailed numerical study based on 954 problems from the CUTEr test set. An evaluation is made of several line-search options, and a comparison is provided with two state-of-the-art interior-point codes for nonlinear programming.

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The Lorenz dominance criterion is the centre piece of inequality analysis. Yet, the appeal of this criterion, which requires considering Lorenz curves in their entirety, is undermined by the practical problem that many sample Lorenz curves intersect in the tails. The commonly used inferential

doing so outweigh costs. Using a general dynamic model with MarkovJan aggregate and idiosyncratic uncertainty, we show that efficient arrangements are characterised by a simple updating rule, similar to a simple debt contract with occasional forgiveness. We use Indian village data to test thetheory

The histograms of user ratings (1⋆,..., 10⋆) on the Internet Movie Database (IMDb.com) which are in a mature state (more than 20, 000 ratings) seem to follow common rules. All are either double or triple peaked. Moreover, at most one peak can be on the central bins 2⋆,..., 9 ⋆ and the distribution in these bins looks smooth `Gaussian-like ' while changes at the extremes the often look abrupt. This is well approximated under the assumption that histograms are con ned and discretised probability density functions of Lévy skew α-stable distributions. These distributions are the only stable distributions which could emerge due to a generalized central limit theorem from averaging of various independent random variables as which we see initial opinions of users. Averaging is also an appropriate assumption about the social process which underlies the process of continuous opinion formation. Surprisingly, not the normal distribution achieves the best t over the dataset of 1, 086 movies, but distributions with fat tails which decay as power-laws with exponent −(1+α) (α = 4 3). Parameters of the Lévy skew α-stable distributions seem to depend on the deviation from an average movie (with mean about 7.6⋆). The histogram of an average movie has no skewness and is the most narrow one. If a movie deviates from average the distribution gets broader and skewness appears which pronounces the deviation. This is used to construct a one parameter t which gives some evidence of universality in processes of continuous opinion dynamics about taste. 1