Actors and networks of agroecology in the Greater Mekong Subregion

A comparative analysis of agroecology network led to a classification based on their conditions of emergence, their structure and governance mechanisms. The study points the strengths and weaknesses of the existing networks at the different scales. It shows that the different agroecology schools are not necessarily well coordinated at each level (national, regional, global) nor across levels for each agroecology school. The activities of a regional agroecology learning alliance should be grounded in strong national networks and endorsed by global networks

Optimization of a Geman-McClure like criterion for sparse signal deconvolution

International audienceThis paper deals with the problem of recovering a sparse unknown signal from a set of observations. The latter are obtained by convolution of the original signal and corruption with additive noise. We tackle the problem by minimizing a least-squares fit criterion penalized by a Geman-McClure like potential. The resulting criterion is a rational function, which makes it possible to formulate its minimization as a generalized problem of moments for which a hierarchy of semidefinite programming relaxations can be proposed. These convex relaxations yield a monotone sequence of values which converges to the global optimum. To overcome the computational limitations due to the large number of involved variables, a stochastic block-coordinate descent method is proposed. The algorithm has been implemented and shows promising result