The Role of Diverse Strategies in Sustainable Knowledge Production

Online communities are becoming increasingly important as platforms for large-scale human cooperation. These communities allow users seeking and sharing professional skills to solve problems collaboratively. To investigate how users cooperate to complete a large number of knowledge-producing tasks, we analyze StackExchange, one of the largest question and answer systems in the world. We construct attention networks to model the growth of 110 communities in the StackExchange system and quantify individual answering strategies using the linking dynamics of attention networks. We identify two types of users taking different strategies. One strategy (type A) aims at performing maintenance by doing simple tasks, while the other strategy (type B) aims investing time in doing challenging tasks. We find that the number of type A needs to be twice as big as type B users for a sustainable growth of communities.Comment: 10 pages, 3 figure

False discovery rate: setting the probability of false claim of detection

When testing multiple hypothesis in a survey --e.g. many different source locations, template waveforms, and so on-- the final result consists in a set of confidence intervals, each one at a desired confidence level. But the probability that at least one of these intervals does not cover the true value increases with the number of trials. With a sufficiently large array of confidence intervals, one can be sure that at least one is missing the true value. In particular, the probability of false claim of detection becomes not negligible. In order to compensate for this, one should increase the confidence level, at the price of a reduced detection power. False discovery rate control is a relatively new statistical procedure that bounds the number of mistakes made when performing multiple hypothesis tests. We shall review this method, discussing exercise applications to the field of gravitational wave surveys.Comment: 7 pages, 3 table, 3 figures. Prepared for the Proceedings of GWDAW 9 (http://lappc-in39.in2p3.fr/GWDAW9) A new section was added with a numerical example, along with two tables and a figure related to the new section. Many smaller revisions to improve readibilit

Timbó: uma alternativa para a produção perene de adubo verde.

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Possibilidades de Gliricidia sepium (Jacq.) Steud para uso em sistemas agroflorestais no Brasil

This paper describes Gliricidia sepium species, its importance and utilization for multiple uses in agroforestry systems through the tropical world. In account to introduce and utilize this species in Brazil, the possibilities of its use in appropriated ecological zones are discussed.O trabalho descreve a espécie Gliricidia sepium, sua importância e múltiplos usos em sistemas agroflorestais, em diversas regiões tropicais, dando ênfase para o potencial que representa para algumas regiões do Brasil

Sistema agroflorestal grevílea x cafe: início de nova era na agricultura paranaense?

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Sinopse de algumas vantagens e desvantagens dos sistemas silvipastoris com Pinus spp.

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