Memória de horta orgânica comunitária em solo urbano

Pesquisa-ação em desenvolvimento junto ao movimento de horta orgânica comunitária Vila Esperança, situado na próspera cidade econômica e tecnologicamente desenvolvida de Campinas (Estado de São Paulo – Brasil), foi idealizada como ação promotora de saúde para ressignificar área pública degradada, utilizada como bota-fora de lixo e resíduos de materiais de construção civil. Em 2007, foi realizada a oficina "Comunidade Saudável" com representantes do poder público, universidade e lideranças comunitárias com perguntas condutoras para responderam “O que é mais importante, possível realizar / proporcionar uma comunidade saudável na região dos Amarais?”. A sugestão foi trabalhar nos eixos saúde, meio ambiente e educação; entre as propostas foi escolhida a implantação de hortas comunitárias. Da proposta inicial de horta comunitária, o movimento passou por várias fases: solicitação de cessão de área pública, fundação de uma Associação para ser a beneficiaria da área, instalação de ponto de água, iniciativas de produção, organização do grupo, orientações para produção de olericultura orgânica. Atualmente o grupo de agricultores e agricultoras da horta recebe orientações para a produção de hortaliças orgânicas. O programa é estruturado em preparo do solo e adubação verde, compostagem, produção de mudas, tratos culturais, pragas e doenças, colheita e comercialização. A pesquisadora acompanha e colabora com o planejamento da implantação da horta comunitária, mantém um caderno de memória das atividades da horta, e através da metodologia de história oral, coleta depoimentos dos agricultores e agricultoras sobre o processo de migração para a região estudada e sobre as transformações territoriais, as questões socioambientais, de saúde e de consolidação da horta comunitária no bairro. Desta experiência formamos um mosaico de histórias que se cruzam e entrecruzam com questões sociais, migração, adensamento populacional, transição entre rural e urbano, mudanças de hábitos e alimentação, qualidade de vida urbana. Entretanto, observamos desafios deste empreendimento: importância do trabalho coletivo, da produção sem uso de agrotóxicos e a sustentabilidade social, econômica e ambiental

Investigation on the Influence of Basalt Fiber on Thermal properties of Al7075/ Basalt Fiber Metal Matrix Composites.

This paper reports a study of the Coefficient of Thermal Expansion (CTE) of Al7075/basalt short fiber Metal Matrix Composites (MMCs) as a function of temperature and reinforcement. The percentage of reinforcement was varied from 2.5 to 10 wt. % in steps of 2.5% and the composites were prepared by the liquid metallurgy technique. Using Thermal Mechanical Analyzer (TMA) model DuPont 943 equipment, the changes in the linear dimension as a function of temperature is recorded as Percent Linear Change (PLC). The temperature of the tests ranged from 50 °C to 300 °C in the steps of 5 °C both in the heating and cooling cycles. The results show that the CTE significantly increased with increasing temperature but decreased with increasing basalt fiber. These phenomena are explained

4D STEM: high efficiency phase contrast imaging using a fast pixelated detector

Phase contrast imaging is widely used for imaging beam sensitive and weak phase objects in electron microscopy. In this work we demonstrate the achievement of high efficient phase contrast imaging in STEM using the pnCCD, a fast direct electron pixelated detector, which records the diffraction patterns at every probe position with a speed of 1000 to 4000 frames per second, forming a 4D STEM dataset simultaneously with the incoherent Z-contrast imaging. Ptychographic phase reconstruction has been applied and the obtained complex transmission function reveals the phase of the specimen. The results using GaN and Ti, Nd- doped BiFeO3 show that this imaging mode is especially powerful for imaging light elements in the presence of much heavier elements

An Effective Membrane Model of the Immunological Synapse

The immunological synapse is a patterned collection of different types of receptors and ligands that forms in the intercellular junction between T Cells and antigen presenting cells (APCs) during recognition. The synapse is implicated in information transfer between cells, and is characterized by different spatial patterns of receptors at different stages in the life cycle of T cells. We obtain a minimalist model that captures this experimentally observed phenomenology. A functional RG analysis provides further insights.Comment: 6 pages, 3 figures, submitted for publicatio

Measuring the proton spectrum in neutron decay - latest results with aSPECT

The retardation spectrometer aSPECT was built to measure the shape of the proton spectrum in free neutron decay with high precision. This allows us to determine the antineutrino electron angular correlation coefficient a. We aim for a precision more than one order of magnitude better than the present best value, which is Delta_a /a = 5%. In a recent beam time performed at the Institut Laue-Langevin during April / May 2008 we reached a statistical accuracy of about 2% per 24 hours measurement time. Several systematic effects were investigated experimentally. We expect the total relative uncertainty to be well below 5%.Comment: Accepted for publication in the Conference Proceedings of the International Workshop on Particle Physics with Slow Neutrons 2008 held at the ILL, France. To be published in Nuclear Instruments and Methods in Physics Research, Section

A homological interpretation of the transverse quiver Grassmannians

In recent articles, the investigation of atomic bases in cluster algebras associated to affine quivers led the second-named author to introduce a variety called transverse quiver Grassmannian and the first-named and third-named authors to consider the smooth loci of quiver Grassmannians. In this paper, we prove that, for any affine quiver Q, the transverse quiver Grassmannian of an indecomposable representation M is the set of points N in the quiver Grassmannian of M such that Ext^1(N,M/N)=0. As a corollary we prove that the transverse quiver Grassmannian coincides with the smooth locus of the irreducible components of minimal dimension in the quiver Grassmannian.Comment: final version, 7 pages, corollary 1.2 has been modifie

Effects of disorder in location and size of fence barriers on molecular motion in cell membranes

The effect of disorder in the energetic heights and in the physical locations of fence barriers encountered by transmembrane molecules such as proteins and lipids in their motion in cell membranes is studied theoretically. The investigation takes as its starting point a recent analysis of a periodic system with constant distances between barriers and constant values of barrier heights, and employs effective medium theory to treat the disorder. The calculations make possible, in principle, the extraction of confinement parameters such as mean compartment sizes and mean intercompartmental transition rates from experimentally reported published observations. The analysis should be helpful both as an unusual application of effective medium theory and as an investigation of observed molecular movements in cell membranes.Comment: 9 pages, 5 figure

Rupture of multiple parallel molecular bonds under dynamic loading

Biological adhesion often involves several pairs of specific receptor-ligand molecules. Using rate equations, we study theoretically the rupture of such multiple parallel bonds under dynamic loading assisted by thermal activation. For a simple generic type of cooperativity, both the rupture time and force exhibit several different scaling regimes. The dependence of the rupture force on the number of bonds is predicted to be either linear, like a square root or logarithmic.Comment: 8 pages, 2 figure

Elastic deformation of a fluid membrane upon colloid binding

When a colloidal particle adheres to a fluid membrane, it induces elastic deformations in the membrane which oppose its own binding. The structural and energetic aspects of this balance are theoretically studied within the framework of a Helfrich Hamiltonian. Based on the full nonlinear shape equations for the membrane profile, a line of continuous binding transitions and a second line of discontinuous envelopment transitions are found, which meet at an unusual triple point. The regime of low tension is studied analytically using a small gradient expansion, while in the limit of large tension scaling arguments are derived which quantify the asymptotic behavior of phase boundary, degree of wrapping, and energy barrier. The maturation of animal viruses by budding is discussed as a biological example of such colloid-membrane interaction events.Comment: 14 pages, 9 figures, REVTeX style, follow-up on cond-mat/021242

Gorenstein homological algebra and universal coefficient theorems

We study criteria for a ring—or more generally, for a small category—to be Gorenstein and for a module over it to be of finite projective dimension. The goal is to unify the universal coefficient theorems found in the literature and to develop machinery for proving new ones. Among the universal coefficient theorems covered by our methods we find, besides all the classic examples, several exotic examples arising from the KK-theory of C*-algebras and also Neeman’s Brown–Adams representability theorem for compactly generated categories