5,843 research outputs found

    A history of demands: philosophy and agrobiology. The significance of the founding principles of organic farming within the framework of contemporary development

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    Organic farming originally deals with the problematic nature/technique within a holistic view. The order of things inspires organic agronomy and social thoughts on agriculture. The link between what is and what has to be socially is not thinkable within modern right and ethic, but it is in accordance with the ancient philosophy. A. Howard, R. Steiner, H.P. Rusch, M. Fukuoka, found their biology according to this fundamental way of behaving. The biology of those founders stands between various philosophical speculations, esoteric speculations, empirical observations, and scientific approaches. According to the ancient philosophy, these authors are suggesting an imitation of nature based on a cyclic understanding. Human intrusion in nature, although founding element of farming, remains hard to legitimate. Indeed the founders are anxious about the agricultural chemistry’s consequences on ecology and society. Today the biological foundation of organic farming could cross again with evolutionism and ecology. A more dynamic conception of nature will open new ways for agronomic reasoning. This also opens up on a more humanistic philosophy of farming. Nevertheless, the holistic ethic of organic farming remains an innovating source for its contemporary development

    Stabilized Schemes for the Hydrostatic Stokes Equations

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    Some new stable finite element (FE) schemes are presented for the hydrostatic Stokes system or primitive equations of the ocean. It is known that the stability of the mixed formulation ap- proximation for primitive equations requires the well-known Ladyzhenskaya–Babuˇska–Brezzi condi- tion related to the Stokes problem and an extra inf-sup condition relating the pressure and the vertical velocity. The main goal of this paper is to avoid this extra condition by adding a residual stabilizing term to the vertical momentum equation. Then, the stability for Stokes-stable FE combinations is extended to the primitive equations and some error estimates are provided using Taylor–Hood P2 –P1 or miniele- ment (P1 +bubble)–P1 FE approximations, showing the optimal convergence rate in the P2 –P1 case. These results are also extended to the anisotropic (nonhydrostatic) problem. On the other hand, by adding another residual term to the continuity equation, a better approximation of the vertical derivative of pressure is obtained. In this case, stability and error estimates including this better approximation are deduced, where optimal convergence rate is deduced in the (P 1 +bubble)–P1 case. Finally, some numerical experiments are presented supporting previous results

    Charm meson resonances in D→Pâ„“ÎœD \to P \ell \nu decays

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    Motivated by recent experimental results we reconsider semileptonic D→PℓΜℓD \to P \ell \nu_{\ell} decays within a model which combines heavy quark symmetry and properties of the chiral Lagrangian. We include excited charm meson states, some of them recently observed, in our Lagrangian and determine their impact on the charm meson semileptonic form factors. We find that the inclusion of excited charm meson states in the model leads to a rather good agreement with the experimental results on the q2q^2 shape of the F+(q2)F_+(q^2) form factor. We also calculate branching ratios for all D→PℓΜℓD \to P \ell \nu_{\ell} decays.Comment: 9 pages, 4 figures; minor corrections, added some discussion, version as publishe

    Chiral radiative corrections and D_s(2317)/D(2308) mass puzzle

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    We show that one loop chiral corrections for heavy-light mesons in potential model can explain the small mass of D_s(2317) as well as the small mass gap between D_s(2317) and D(2308).Comment: To appear in EPJC. A figure and references addede

    Becoming a (green) identity entrepreneur: learning to negotiate situated identities to nurture community environmental practice

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    This paper explores the relationship between ‘green’ identity and community environmental practice. It focuses on the ways in which professional community development facilitators and lead members of community groups attempt to actively shape how environmental projects are locally received. Drawing principally on identity, social sustainability and social practice theory scholarship, it reviews the often very personal and place-specific ways in which appeals to green identity are variously understood and applied, or are actively avoided, by community group leaders. Individuals who have become skilful in negotiating and influencing the presentation of environmental projects to the local community are understood here as (green) identity entrepreneurs. Arguably, it is the situated entrepreneurial skilfulness of lead individuals in negotiating the multiple and evolving (green) identities circulating through any one project, which plays a significant part in determining its subsequent impact and longevity. In understanding the contribution of (green) identity entrepreneurship, however, its relational association with everyday practices, routines and meanings of community and place is brought to the fore. The paper also considers how divergent external interpretations of what constitutes legitimate environmental practice at a local level further shape project identity. The discussion is informed by evidence drawn from a qualitative study of seventeen community groups and seven professional environmental support officers participating in a Welsh Government led programme aimed at facilitating 'community action on climate change'

    Charm as a domain wall fermion in quenched lattice QCD

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    We report a study describing the charm quark by a domain-wall fermion (DWF) in lattice quantum chromodynamics (QCD). Our study uses a quenched gauge ensemble with the DBW2 rectangle-improved gauge action at a lattice cutoff of a−1∌3a^{-1} \sim 3 GeV. We calculate masses of heavy-light (charmed) and heavy-heavy (charmonium) mesons with spin-parity JP=0∓J^P = 0^\mp and 1∓1^\mp, leptonic decay constants of the charmed pseudoscalar mesons (DD and DsD_s), and the D0D^0-D0ˉ\bar{D^0} mixing parameter. The charm quark mass is found to be mcMSˉ(mc)=1.24(1)(18)m^{\bar{\rm MS}}_{c}(m_{c})=1.24(1)(18) GeV. The mass splittings in charmed-meson parity partners Δq,J=0\Delta_{q,J=0} and Δq,J=1\Delta_{q, J=1} are degenerate within statistical errors, in accord with experiment, and they satisfy a relation Δq=ud,J>Δq=s,J\Delta_{q=ud, J} > \Delta_{q=s, J}, also consistent with experiment. A C-odd axial vector charmonium state, hc),lies22(11)MeVabovetheh_c), lies 22(11) MeV above the \chi_{c1}meson,or meson, or m_{h_{c}} = 3533(11)_{\rm stat.}MeVusingtheexperimental MeV using the experimental \chi_{c1}) mass. However, in this regard, we emphasize significant discrepancies in the calculation of hyperfine splittings on the lattice. The leptonic decay constants of DD and DsD_s mesons are found to be fD=232(7)stat.(−0+6)chiral(11)syst.f_D=232(7)_{\rm stat.}(^{+6}_{-0})_{\rm chiral}(11)_{\rm syst.} MeV and fDs/fD=1.05(2)stat.(−2+0)chiral(2)syst.f_{D_s}/f_{D} = 1.05(2)_{\rm stat.}(^{+0}_{-2})_{\rm chiral}(2)_{\rm syst.}, where the first error is statistical, the second a systematic due to chiral extrapolation and the third error combination of other known systematics. The D0D^0-D0ˉ\bar{D^0} mixing bag parameter, which enters the ΔC=2\Delta C = 2 transition amplitude, is found to be BD(2GeV)=0.845(24)stat.(−6+24)chiral(105)syst.B_D(2{GeV})=0.845(24)_{\rm stat.}(^{+24}_{-6})_{\rm chiral}(105)_{\rm syst.}.Comment: 49 pages, 15 figure

    Chiral doublers of heavy-light baryons

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    We discuss the consequences of the chiral doubling scenario for baryons built of heavy and light quarks. In particular, we use the soliton description for baryons, demonstrating why each heavy-light baryon should be accompanied by the opposite parity partner. Our argumentation holds both for ordinary baryons and for exotic heavy pentaquarks which are required by the symmetries of QCD to appear in parity doublets, seperated by the mass shift of the chiral origin. Interpreting the recently observed by BaBaR, CLEO and Belle charmed mesons with assignment (0+,1+)(0^+,1^+) as the chiral partners of known DD and D∗D^* mesons, allows us to estimate the parameters of the mesonic effective lagrangian, and in consequence, estimate the masses of ground states and excited states of both parities. In particular, we interpret the state recently reported by the H1 experiment at HERA as a chiral partner Θ~c0(3099)\tilde{\Theta}_c^0(3099) of yet undiscovered ground state pentaquark Θc0(2700)\Theta_c^0(2700).Comment: 10 pages, in v2 some typos corrected, references adde

    Dominant Topologies in Euclidean Quantum Gravity

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    The dominant topologies in the Euclidean path integral for quantum gravity differ sharply according on the sign of the cosmological constant. For Λ>0\Lambda>0, saddle points can occur only for topologies with vanishing first Betti number and finite fundamental group. For Λ<0\Lambda<0, on the other hand, the path integral is dominated by topologies with extremely complicated fundamental groups; while the contribution of each individual manifold is strongly suppressed, the ``density of topologies'' grows fast enough to overwhelm this suppression. The value Λ=0\Lambda=0 is thus a sort of boundary between phases in the sum over topologies. I discuss some implications for the cosmological constant problem and the Hartle-Hawking wave function.Comment: 14 pages, LaTeX. Minor additions (computability, relation to ``minimal volume'' in topology); error in eqn (3.5) corrected; references added. To appear in Class. Quant. Gra

    Semileptonic Bs ->DsJ(2460)l nu decay in QCD

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    Using three point QCD sum rules method, the form factors relevant to the semileptonic Bs ->DsJ (2460)l nu decay are calculated. The q2 dependence of these form factors is evaluated and compared with the heavy quark effective theory predictions. The dependence of the asymmetry parameter alpha, characterizing the polarization of DsJ meson, on q2 is studied .The branching ratio of this decay is also estimated and is shown that it can be easily detected at LHC.Comment: 21 pages, 5 figures and 1 Tabl
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