14,530 research outputs found

    Outcomes of CCAFS Work in Vietnam

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    The study explored how CCAFS SEA outputs have helped the country achieve its development outcomes in the agricultural sector. The assessment showed that CCAFS SEA, although still on-going, has contributed to specific outcomes in Vietnam, which include changes in knowledge, approaches, practices, and strategies related to climate change, particularly in the agricultural sector. These outcomes were observed among decision makers, policymakers, technical staff, and farmers

    Effects of Bose-Einstein Condensation on forces among bodies sitting in a boson heat bath

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    We explore the consequences of Bose-Einstein condensation on two-scalar-exchange mediated forces among bodies that sit in a boson gas. We find that below the condensation temperature the range of the forces becomes infinite while it is finite at temperatures above condensation.Comment: 10 pages, 2 figure

    Revision of the types of species of Alloxysta described by Cameron and Fergusson (Hymenoptera: Figitidae: Charipinae) and deposited in the Natural History Museum (London), including a key to the fauna of Great Britain

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    Type material of the species of Alloxysta described by Cameron and Fergusson and deposited in the Natural History Museum of London has been revised. Seven species are considered valid: Alloxysta abdera Fergusson, 1986, A. basimacula (Cameron, 1886), A. crassa (Cameron, 1889), A. mullensis (Cameron, 1883), A. piceomaculata (Cameron, 1883), A. pleuralis (Cameron, 1879) and A. semiaperta Fergusson, 1986. A. basimacula, A. crassa, A. maculicollis (Cameron, 1886), A. perplexa (Cameron, 1889) and A. piceomaculata are here removed from synonymy with A. macrophadna (Hartig, 1841). A. rufi ceps (Cameron, 1883) is removed from synonymy with A. victrix (Westwood, 1833). A. caledonica (Cameron, 1886) and A. perplexa are here synonymized with A. basimacula. A. maculicollis, A. ruficeps and A. ruficollis (Cameron, 1883) are here synonymized with A. castanea (Hartig, 1841). A. ancylocera (Cameron, 1886) was correctly synonymized with A. fuscicornis (Hartig, 1841), A. curvicornis (Cameron, 1883) was correctly synonymized with A. victrix and A. filicornis (Cameron, 1889) was correctly synonymized with A. macrophadna. Complete redescriptions and illustrations are given for valid species. A key for all the Alloxysta species found so far in Great Britain is given

    Long range neutrino forces in the cosmic relic neutrino background

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    Neutrinos mediate long range forces among macroscopic bodies in vacuum. When the bodies are placed in the neutrino cosmic background, these forces are modified. Indeed, at distances long compared to the scale T−1T^{-1}, the relic neutrinos completely screen off the 2-neutrino exchange force, whereas for small distances the interaction remains unaffected.Comment: 8 pages, 2 figure

    Demographic growth and the distribution of language sizes

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    It is argued that the present log-normal distribution of language sizes is, to a large extent, a consequence of demographic dynamics within the population of speakers of each language. A two-parameter stochastic multiplicative process is proposed as a model for the population dynamics of individual languages, and applied over a period spanning the last ten centuries. The model disregards language birth and death. A straightforward fitting of the two parameters, which statistically characterize the population growth rate, predicts a distribution of language sizes in excellent agreement with empirical data. Numerical simulations, and the study of the size distribution within language families, validate the assumptions at the basis of the model.Comment: To appear in Int. J. Mod. Phys. C (2008

    Exact Kohn-Sham eigenstates versus quasiparticles in simple models of strongly correlated electrons

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    We present analytic expressions for the exact density functional and Kohn-Sham Hamiltonian of simple tight-binding models of correlated electrons. These are the single- and double-site versions of the Anderson, Hubbard and spinless fermion models. The exact exchange and correlation potentials are fully non-local. The analytic expressions allow to compare the Kohn-Sham eigenstates of exact density functional theory with the many-body quasi-particle states of these correlated-electron systems. The exact Kohn-Sham spectrum describes correctly many of the non-trivial features of the many-body quasi-particle spectrum, as for example the precursors of the Kondo peak. However, we find that some pieces of the quasi-particle spectrum are missing because the many-body phase-space for electron and hole excitations is richer
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