5,525 research outputs found

    Reshaping institutions : bricolage processes in smallholder forestry in the Amazon

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    This thesis aims at identifying the different kinds of institutional influences on forest practices of small farmers in the Amazon region of Ecuador and Bolivia and how small farmers respond to them. It departs from the perspective that institutions affecting forest practices are subject to processes of institutional bricolage in which small farmers construct their own institutional frameworks by aggregating, altering, or articulating elements of existing disparate institutions. This research demonstrates that institutions, whether introduced by government, NGO, or already existing, are subject to processes of institutional bricolage that can be either conscious and strategic of nature or less conscious and unintentional

    Finite temperature molecular dynamics study of unstable stacking fault free energies in silicon

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    We calculate the free energies of unstable stacking fault (USF) configurations on the glide and shuffle slip planes in silicon as a function of temperature, using the recently developed Environment Dependent Interatomic Potential (EDIP). We employ the molecular dynamics (MD) adiabatic switching method with appropriate periodic boundary conditions and restrictions to atomic motion that guarantee stability and include volume relaxation of the USF configurations perpendicular to the slip plane. Our MD results using the EDIP model agree fairly well with earlier first-principles estimates for the transition from shuffle to glide plane dominance as a function of temperature. We use these results to make contact to brittle-ductile transition models.Comment: 6 pages revtex, 4 figs, 16 refs, to appear in Phys. Rev.

    Problems in Treating Experimentally Induced Acute Hepatic Failure by Hemoperfusion or Cross Circulation

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    Acute hepatic failure was induced in rats by galactosamine injection intraperitoneally (1 gm per kg). Twenty-four hours later rats were treated by hemoperfusion (HP) over encapsulated sorbents: cellulose acetate-coated charcoal, polyelectrolyte-coated XAD4, a combination of both, or cross circulation with a healthy donor. Compared with control treatment (prevention of hypoglycemia by glucose infusion), the survival rate was not improved by HP or cross circulation: controls 19% vs. treated animals 0 to 17%. Extension of duration or increased frequency of HP gave the same survival rates. Computer simulation based on zero-order introduction of a possible toxin into a two-compartment model shows that HP up to 5 hr per day is not able to clear the body effectively from the assumed toxin if its partition coefficient exceeds a value of 50

    Spin-mediated dissipation and frequency shifts of a cantilever at milliKelvin temperatures

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    We measure the dissipation and frequency shift of a magnetically coupled cantilever in the vicinity of a silicon chip, down to 2525 mK. The dissipation and frequency shift originates from the interaction with the unpaired electrons, associated with the dangling bonds in the native oxide layer of the silicon, which form a two dimensional system of electron spins. We approach the sample with a 3.433.43 μ\mum-diameter magnetic particle attached to an ultrasoft cantilever, and measure the frequency shift and quality factor as a function of temperature and the distance. Using a recent theoretical analysis [J. M. de Voogd et al., arXiv:1508.07972 (2015)] of the dynamics of a system consisting of a spin and a magnetic resonator, we are able to fit the data and extract the relaxation time T1=0.39±0.08T_1=0.39\pm0.08 ms and spin density σ=0.14±0.01\sigma=0.14\pm0.01 spins per nm2^2. Our analysis shows that at temperatures 500\leq500 mK magnetic dissipation is an important source of non-contact friction.Comment: 5 pages, 3 figure

    Naval Vessel Traffic Services

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    Vessel traffic services (VTSs) ensure the safe and efficient handling of traffic on busy waterways like the English Channel and the approaches to New York. This technique, wherein electronic sensors and communication systems are used to manage traffic actively, can also be used in maritime security operations (MSOs) to enhance safety in areas with risks related to asymmetric threats.1 Nowadays a limited form of VTS is deployed for MSO situated in international waters. These services, provided by naval cooperation and guidance for shipping (NCAGS) organizations, are focused on building maritime domain awareness (MDA) and providing naval-related safety information to merchant shipping
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