Properties of finite dual fusion frames

A new notion of dual fusion frame has been recently introduced by the authors. In this article that notion is further motivated and it is shown that it is suitable to deal with questions posed in a finite-dimensional real or complex Hilbert space, reinforcing the idea that this concept of duality solves the question about an appropriate definition of dual fusion frames. It is shown that for overcomplete fusion frames there always exist duals different from the canonical one. Conditions that assure the uniqueness of duals are given. The relation of dual fusion frame systems with dual frames and dual projective reconstruction systems is established. Optimal dual fusion frames for the reconstruction in case of erasures of subspaces, and optimal dual fusion frame systems for the reconstruction in case of erasures of local frame vectors are determined. Examples that illustrate the obtained results are exhibited.Fil: Heineken, Sigrid Bettina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Morillas, Patricia Mariela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; Argentin

Foreign Direct Investments or Economic Exploitation of Developing Countries? A Critical Discourse on the Concept of `Land grabbing’ in Africa

Since 2008 there has been a dramatic increase in foreign direct investments in large-scale agriculture in Africa. This has manifested in the acquisition, by foreign entities, of millions of hectares of lands in African countries and has given rise to the concept of `land grabbing in Africa’. This article critically evaluates various existing studies on the concept of `land grabbing in Africa’, and argues that the dramatic rise in foreign investments in agriculture in developing countries does not necessarily mean `land grabbing’. The article proposes a significant distinction between large-scale foreign investments in agriculture, which African countries direly need, and the concept of land grabbing as commonly used in existing literature. The article cautions that the resounding shouts about land grabbing should not drown the urgent whispers of the necessity of foreign investments in large-scale agriculture to the economic productivity and development of African countries. The article points the way forward for African governments to ensure that foreign investments in large-scale agriculture do not result to economic exploitation or land grabbing but contribute to national productivity and economic development of the continent. Keywords: Large-scale agriculture, land grabbing, foreign direct investment, African development, economic exploitatio