5,631 research outputs found

    Public policies and food security and family farming networks: contributions to the construction of effectiveness indicators.

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    This work presents a methodology for investigating the performance of public politics regarding food security networks formed in Brazilian municipalities aimed at increasing income and employment in familiar farming. These programs need to further develop the methodologies used for studying their efficiency so that they can reach a new stage in the improvement and use of management tools thereby achieving beteer results of social inclusion and/or food security. This paper constitutes a first effort to bring together indicators for the evaluation of the efficiency of public politicies

    Quantum simulation of the Anderson Hamiltonian with an array of coupled nanoresonators: delocalization and thermalization effects

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    The possibility of using nanoelectromechanical systems as a simulation tool for quantum many-body effects is explored. It is demonstrated that an array of electrostatically coupled nanoresonators can effectively simulate the Bose-Hubbard model without interactions, corresponding in the single-phonon regime to the Anderson tight-binding model. Employing a density matrix formalism for the system coupled to a bosonic thermal bath, we study the interplay between disorder and thermalization, focusing on the delocalization process. It is found that the phonon population remains localized for a long time at low enough temperatures; with increasing temperatures the localization is rapidly lost due to thermal pumping of excitations into the array, producing in the equilibrium a fully thermalized system. Finally, we consider a possible experimental design to measure the phonon population in the array by means of a superconducting transmon qubit coupled to individual nanoresonators. We also consider the possibility of using the proposed quantum simulator for realizing continuous-time quantum walks.Comment: Replaced with new improved version. To appear in EPJ Q

    Molecular dynamics study of accelerated ion-induced shock waves in biological media

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    We present a molecular dynamics study of the effects of carbon- and iron-ion induced shock waves in DNA duplexes in liquid water. We use the CHARMM force field implemented within the MBN Explorer simulation package to optimize and equilibrate DNA duplexes in liquid water boxes of different sizes and shapes. The translational and vibrational degrees of freedom of water molecules are excited according to the energy deposited by the ions and the subsequent shock waves in liquid water are simulated. The pressure waves generated are studied and compared with an analytical hydrodynamics model which serves as a benchmark for evaluating the suitability of the simulation boxes. The energy deposition in the DNA backbone bonds is also monitored as an estimation of biological damage, something which is not possible with the analytical model

    Mass Density Profiles of LSB Galaxies

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    We derive the mass density profiles of dark matter halos that are implied by high spatial resolution rotation curves of low surface brightness galaxies. We find that at small radii, the mass density distribution is dominated by a nearly constant density core with a core radius of a few kpc. For rho(r) ~ r^a, the distribution of inner slopes a is strongly peaked around a = -0.2. This is significantly shallower than the cuspy a < -1 halos found in CDM simulations. While the observed distribution of alpha does have a tail towards such extreme values, the derived value of alpha is found to depend on the spatial resolution of the rotation curves: a ~ -1 is found only for the least well resolved galaxies. Even for these galaxies, our data are also consistent with constant density cores (a = 0) of modest (~ 1 kpc) core radius, which can give the illusion of steep cusps when insufficiently resolved. Consequently, there is no clear evidence for a cuspy halo in any of the low surface brightness galaxies observed.Comment: To be published in ApJ Letters. 6 pages. Uses aastex and emulateapj5.sty Typo in Eq 1 fixe

    Ferramentas tecnológicas ajudaram a sociedade civil brasileira no trabalho com migrantes durante a pandemia, mas não substituem transformações duradouras

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    Organizações da sociedade civil ofereceram apoio vital a populações migrantes e refugiadas no Brasil durante a crise do COVID-19. Muitas delas foram forçadas a adaptar seus programas a fim de lidar com a crescente demanda por ajuda emergencial, com a expansão do uso das tecnologias permitindo um novo modelo híbrido de trabalho. Porém, mesmo com todos os problemas que ajuda a solucionar, a tecnologia também pode levantar novas questões e, em última análise, não deve ser vista como substituto para soluções duráveis, escrevem Marcia Vera Espinoza (Queen Mary University of London), Gisela P. Zapata (Universidade Federal de Minas Gerais) e Flavia R. Castro (PUC-Rio)

    Kombucha microbiome as a probiotic: a view from the perspective of post-genomics and synthetic ecology

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    Probiotics are essential for establishing and maintaining optimal immune health. The probiotic therapy is known from alternative medicine for ages; however, the recent demonstration of the normal microflora to induce innate immunity has introduced the science-based concept of therapeutic application of potentially beneficial probiotic microorganisms for a treatment of functional disorders. Traditionally, probiotics are associated with dairy products, however, novel formulations are needed, first of all, originated from naturally occurring symbiotic microbial communities as the most robust assemblages. Especially, safe and robust probiotics are needed for long-term expeditions, outposts, extraterrestrial permanently-manned bases, where humans are exposed to adverse environmental factors. Kombucha beverage is Symbiotic Culture of Bacteria and Yeast (SCOBY) and associated with health-promoting effects. Kombucha tea/mat is being in use in human livings within millennia as a probiotic drink for healing and health prophylaxis effects, however, new research opportunities promise its «renaissance», going to be used pharmacologically
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