1,822 research outputs found

    Evaluation of agricultural ecosystem services in fallowing land based on farmers' participation and model simulation

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    Fallowing with green fertilizer can benefit agricultural ecosystem services (AES). Farmers in Taiwan do not implement fallow practices and plant green fertilizer because the current subsidy level (46,000 NTperha)istoolowtomanagefallowing.Thispaperdefinestheobjectiveofgovernmentagriculturepolicyorthefarmersobjectiveasmaximizationoffarmproductivity,approximatedtothevalueofsocialwelfareandAES.Farms,whichdonotfollowproperfallowingpractices,oftenhavepoorlymaintainedfallowlandorleftfarmlandabandoned.Thisresultsinnegativeenvironmentalconsequencessuchascutworminfestationsinabandonedland,whichinturncanaffectcropsinadjacentfarmlands.Theobjectivesofthisstudyaretwofold.First,itdeterminestheproperfallowingsubsidybasedontheconceptofpaymentforecosystemservicestoenticemorefarmerstoparticipateinfallowing.Second,itsimulatesthebenefitofplantinggreenmanureinfallowlandtothesupplyofAESbasedontherateoffarmerswhoarewillingtoparticipateinfallowlandpracticesandessentialparametersthatcanaffectsoilfertilitychange.Theapproachinvolvesaseriesofinterviewsandadevelopedempiricalmodel.ThevalueofAESwhentherateoffarmerparticipationis100 per ha) is too low to manage fallowing. This paper defines the objective of government agriculture policy or the farmer’s objective as maximization of farm productivity, approximated to the value of social welfare and AES. Farms, which do not follow proper fallowing practices, often have poorly maintained fallow land or left farmland abandoned. This results in negative environmental consequences such as cutworm infestations in abandoned land, which in turn can affect crops in adjacent farmlands. The objectives of this study are twofold. First, it determines the proper fallowing subsidy based on the concept of payment for ecosystem services to entice more farmers to participate in fallowing. Second, it simulates the benefit of planting green manure in fallow land to the supply of AES based on the rate of farmers who are willing to participate in fallow land practices and essential parameters that can affect soil fertility change. The approach involves a series of interviews and a developed empirical model. The value of AES when the rate of farmer participation is 100% represents a 1.5% increase in AES (448,317,000 NTperha)istoolowtomanagefallowingThispaperdefinestheobjectiveofgovernmentagriculturepolicyorthefarmer’sobjectiveasmaximizationoffarmproductivityapproximatedtothevalueofsocialwelfareandAESFarmswhichdonotfollowproperfallowingpracticesoftenhavepoorlymaintainedfallowlandorleftfarmlandabandonedThisresultsinnegativeenvironmentalconsequencessuchascutworminfestationsinabandonedlandwhichinturncanaffectcropsinadjacentfarmlandsTheobjectivesofthisstudyaretwofoldFirstitdeterminestheproperfallowingsubsidybasedontheconceptofpaymentforecosystemservicestoenticemorefarmerstoparticipateinfallowingSeconditsimulatesthebenefitofplantinggreenmanureinfallowlandtothesupplyofAESbasedontherateoffarmerswhoarewillingtoparticipateinfallowlandpracticesandessentialparametersthatcanaffectsoilfertilitychangeTheapproachinvolvesaseriesofinterviewsandadevelopedempiricalmodelThevalueofAESwhentherateoffarmerparticipationis100 ) over the value at the current participation rate of 14%. This study further concludes that the appropriate fallowing subsidy has a large positive impact on AES and social welfare (e.g., benefit from food and biofuel supplies) and is seen as a basis of ecological governance for sustainable agro-ecosystems

    Shaping citizenship in the classroom:Peer influences on moral disengagement, social goals, and a sense of peer community

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    Despite the important role of peers in the social process of classroom citizenship, the peer influence related to moral disengagement, social goals, and a sense of peer community remain unclear. To this end, it was examined to what extent youth become similar to their friends in moral disengagement, social goals, and a sense of peer community. Participants were 283 South Korean third to sixth graders (Mage = 9.60 years, SD = 0.97; 51.6% girls) who completed an online survey for moral disengagement, social goals, the sense of peer community and friendship network across the beginning (Time 1) and end (Time 2) of the school semester (September to December). Longitudinal social network analyses indicated that youth became more similar to their friends concerning moral disengagement and a sense of peer community, but did not select friends based on these aspects. The strength of these influence effects varied in terms of different levels of these aspects. Specifically, youth were more likely to become similar to their friends at lower levels of moral disengagement. Youth tended to be similar to the friends' level of sense of peer community. This tendency was relatively strong at the lowest and the highest levels of a sense of peer community. Future research should address the role of friendship in shaping classroom citizenship and the importance of classroom daily teaching practice in youth citizenship development

    On the Couplings of Vector Mesons in AdS/QCD

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    We address, in the AdS/CFT context, the issue of the universality of the couplings of the rho meson to other hadrons. Exploring some models, we find that generically the rho-dominance prediction f_\rho g_{\rho H H}=m_\rho^2 does not hold, and that g_{\rho H H} is not independent of the hadron H. However, we prove that, in any model within the AdS/QCD context, there are two limiting regimes where the g_{\rho H H}, along with the couplings of all excited vector mesons as well, become H-independent: (1) when H is created by an operator of large dimension, and (2) when H is a highly-excited hadron. We also find a sector of a particular model where universality for the rho coupling is exact. Still, in none of these cases need it be true that f_\rho g_\rho=m_\rho^2, although we find empirically that the relation does hold approximately (up to a factor of order two) within the models we have studied.Comment: 28 pages, 3 figures. ver 2: Comments about the commutability of two universal limits in the D3/D7 case corrected. Typos corrected. ver 3: Substantive revisions of certain calculations, with improved conventions, correction of typos, clarifications, new formulas, new figures; no changes in essential results or conclusion

    Vertex functions for d-wave mesons in the light-front approach

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    While the light-front quark model (LFQM) is employed to calculate hadronic transition matrix elements, the vertex functions must be pre-determined. In this work we derive the vertex functions for all d-wave states in this model. Especially, since both of 3D1^3D_1 and 3S1^3S_1 are 11^{--} mesons, the Lorentz structures of their vertex functions are the same. Thus when one needs to study the processes where 3D1^3D_1 is involved, all the corresponding formulas for 3S1^3S_1 states can be directly applied, only the coefficient of the vertex function should be replaced by that for 3D1^3D_1. The results would be useful for studying the newly observed resonances which are supposed to be d-wave mesons and furthermore the possible 2S-1D mixing in ψ\psi' with the LFQM.Comment: 12 pages, 2 figures, some typos corrected and more discussions added. Accepted by EPJ

    The rare top quark decays tcVt\to cV in the topcolor-assisted technicolor model

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    We consider the rare top quark decays in the framework of topcolor-assisted technicolor (TC2) model. We find that the contributions of top-pions and top-Higgs predicted by the TC2 model can enhance the SM branching ratios by as much as 6-9 orders of magnitude. i.e., in the most case, the orders of magnitude of branching ratios are Br(tcg)105Br(t\to c g)\sim 10^{-5}, Br(tcZ)105Br(t\to c Z)\sim 10^{-5}, Br(tcγ)107Br(t\to c \gamma)\sim 10^{-7}. With the reasonable values of the parameters in TC2 model, such rare top quark decays may be testable in the future experiments. So, rare top quark decays provide us a unique way to test TC2 model.Comment: 14 pages, 4 figure

    The creation of large photon-number path entanglement conditioned on photodetection

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    Large photon-number path entanglement is an important resource for enhanced precision measurements and quantum imaging. We present a general constructive protocol to create any large photon number path-entangled state based on the conditional detection of single photons. The influence of imperfect detectors is considered and an asymptotic scaling law is derived.Comment: 6 pages, 4 figure

    Interpolating between low and high energy QCD via a 5D Yang-Mills model

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    We describe the Goldstone bosons of massless QCD together with an infinite number of spin-1 mesons. The field content of the model is SU(Nf)xSU(Nf) Yang-Mills in a compact extra-dimension. Electroweak interactions reside on one brane. Breaking of chiral symmetry occurs due to the boundary conditions on the other brane, away from our world, and is therefore spontaneous. Our implementation of the holographic recipe maintains chiral symmetry explicit throughout. For intermediate energies, we extract resonance couplings. These satisfy sum rules due to the 5D nature of the model. These sum rules imply, when taking the high energy limit, that perturbative QCD constraints are satisfied. We also illustrate how the 5D model implies a definite prescription for handling infinite sums over 4D resonances. Taking the low energy limit, we recover the chiral expansion and the corresponding non-local order parameters. All local order parameters are introduced separately.Comment: Corresponds to published version, with some typos correcte

    Density functional theory of phase coexistence in weakly polydisperse fluids

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    The recently proposed universal relations between the moments of the polydispersity distributions of a phase-separated weakly polydisperse system are analyzed in detail using the numerical results obtained by solving a simple density functional theory of a polydisperse fluid. It is shown that universal properties are the exception rather than the rule.Comment: 10 pages, 2 figures, to appear in PR
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