7,064 research outputs found

    The user structure in Brazil's tropical rain forest

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    This paper presents quantitative evidence on the relationship between forest conversion and the productivity of agropastoral activities in the Legal Amazon. The extraction of timber products such as wood, fuelwood and charcoal is related to the process of agropastoral expansion in this region with the aim of providing physical coefficients to define intersectoral connections in Brazil's economy. The paper is organized as follows. Section I makes a geographical characterization of the original vegetation types of the region according to its principal geopolitical subdivisions. Section II presents evidence on deforestation rates and gross areas affected. Section III describes the principal sources of deforestation. Section IV describes sectoral activities and land occupation patterns distinguishing between forested and non-forested areas. Section V analyses major determinants of productivity in agropastoral activities following this broad vegetation distinction. Section VI provides gross estimates of wood removal associated with agropastoral expansion, and compares this with wood and fuel production figures. Conclusions are presented in Section VII.

    Water Supply or ‘Beautiful Latrines’? Microcredit for Rural Water Supply and Sanitation in the Mekong Delta, Vietnam.

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    Around half of the Mekong Delta’s rural population lacks year-round access to clean water. In combination with inadequate hygiene and poor sanitation this creates a high risk of diseases. Microcredit schemes are a popular element in addressing such problems on the global policy level. The present paper analyses the contradictory results of such a microcredit programme for rural water supply and sanitation in the context of the Mekong Delta, Vietnam, through a qualitative study primarily based on semi-structured interviews in rural communes of Can Tho City. We come to the conclusion that the programme has a positive effect regarding the safer disposal of human excreta as well as surface water quality, but a marginal impact on poverty reduction as it only reaches better-off households already having access to clean water. The paper shows how the outcome of rural water supply and sanitation policies are strongly infl uenced by the local ecological, technological, and social settings, in particular by stakeholders’ interests. The authors challenge the assumption that water supply and sanitation should be integrated into the same policy in all circumstances

    Activity of water in aqueous systems; A frequently neglected property

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    In this critical review, the significance of the term ‘activity’ is examined in the context of the properties of aqueous solutions. The dependence of the activity of water(ℓ) at ambient pressure and 298.15 K on solute molality is examined for aqueous solutions containing neutral solutes, mixtures of neutral solutes and salts. Addition of a solute to water(ℓ) always lowers its thermodynamic activity. For some solutes the stabilisation of water(ℓ) is less than and for others more than in the case where the thermodynamic properties of the aqueous solution are ideal. In one approach this pattern is accounted for in terms of hydrate formation. Alternatively the pattern is analysed in terms of the dependence of practical osmotic coefficients on the composition of the aqueous solution and then in terms of solute–solute interactions. For salt solutions the dependence of the activity of water on salt molalities is compared with that predicted by the Debye–Hückel limiting law. The analysis is extended to consideration of the activities of water in binary aqueous mixtures. The dependence on mole fraction composition of the activity of water in binary aqueous mixtures is examined. Different experimental methods for determining the activity of water in aqueous solutions are critically reviewed. The role of water activity is noted in a biochemical context, with reference to the quality, stability and safety of food and finally with regard to health science.

    Texture-based Tracking in mm-wave Images

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    Current tracking methods rely on color-, intensity-, and edge-based features to compute a description of an image region. These approaches are not well-suited for low-quality images such as mm-wave data from full-body scanners. In order to perform tracking in such challenging grayscale images, we propose several enhancements and extensions to the Visual Tracking Decomposition (VTD) by Kwon and Lee. A novel region descriptor, which uses texture-based features, is presented and integrated into VTD. We improve VTD by adding a sophisticated weighting scheme for observations, better motion models, and a more realistic way for sampling and interaction. Our method not only outperforms VTD on mm-wave data but also has comparable results on normal-quality images. We are confident that our region descriptor can easily be extended to other kinds of features and applications such that tracking can be performed in a large variety of image data, especially low-resolution, low-illumination and noisy images

    Periodic Anderson model with electron-phonon correlated conduction band

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    This paper reports dynamical mean field calculations for the periodic Anderson model in which the conduction band is coupled to phonons. Motivated in part by recent attention to the role of phonons in the γ\gamma-α\alpha transition in Ce, this model yields a rich and unexpected phase diagram which is of intrinsic interest. Specifically, above a critical value of the electron-phonon interaction, a first order transition with two coexisting phases develops in the temperature-hybridization plane, which terminates at a second order critical point. The coexisting phases display the familiar Kondo screened and local moment character, yet they also exhibit pronounced polaronic and bipolaronic properties, respectively.Comment: 4 pages, 6 figure

    Gauge invariance of the background average effective action

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    Using the background field method for the functional renormalization group approach in the case of a generic gauge theory, we study the background field symmetry and gauge dependence of the background average effective action, when the regulator action depends on external fields. The final result is that the symmetry of the average effective action can be maintained for a wide class of regulator functions, but in all cases the dependence of the gauge fixing remains on-shell. The Yang-Mills theory is considered as the main particular example.Comment: Fits the version accepted in EPJ

    The user structure in Brazil's tropical rain forest

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    This paper presents quantitative evidence on the relationship between forest conversion and the productivity of agropastoral activities in the Legal Amazon. The extraction of timber products such as wood, fuelwood and charcoal is related to the process of agropastoral expansion in this region with the aim of providing physical coefficients to define intersectoral connections in Brazil's economy. The paper is organized as follows. Section I makes a geographical characterization of the original vegetation types of the region according to its principal geopolitical subdivisions. Section II presents evidence on deforestation rates and gross areas affected. Section III describes the principal sources of deforestation. Section IV describes sectoral activities and land occupation patterns distinguishing between forested and non-forested areas. Section V analyses major determinants of productivity in agropastoral activities following this broad vegetation distinction. Section VI provides gross estimates of wood removal associated with agropastoral expansion, and compares this with wood and fuel production figures. Conclusions are presented in Section VII
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