1,088 research outputs found

    A multi-stakeholder participatory study identifies the priorities for the sustainability of the small ruminants farming sector in Europe

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    The European small ruminants (i.e. sheep and goats) farming sector (ESRS) provides economic, social and environmental benefits to society, but is also one of the most vulnerable livestock sectors in Europe. This sector has diverse livestock species, breeds, production systems and products, which makes difficult to have a clear vision of its challenges through using conventional analyses. A multi-stakeholder and multi-step approach, including 90 surveys, was used to identify and assess the main challenges for the sustainability of the ESRS to prioritize actions. These challenges and actions were identified by ESRS experts including farmers, cooperatives, breeding associations, advisers and researchers of six EU countries and Turkey. From the 30 identified challenges, the most relevant were economy-related challenges such as ‘uncertainty of meat and milk prices’, ‘volatility of commodity prices’, ‘low farm income’, ‘high subsidy dependency’ and ‘uncertainty in future changes in subsidies’ resulting in ‘a sector not attractive to young farmers’. Most of these challenges were beyond the farmer''s control and perceived as difficult to address. Challenges were prioritized using an index, calculated by multiplying the relevance and the feasibility to address measures. The identified challenges had a similar priority index across the whole sector with small differences across livestock species (sheep vs goats), type of products (meat vs dairy) and intensification levels (intensive vs semi-intensive vs extensive). The priorities were different, however, between socio-geographical regions (Southern vs Central Europe). Some of the top prioritized challenges were linked to aspects related to the production systems (‘low promotion of local breeds’ and ‘slow adaptability of high producing breeds’) and market practices (‘unfair trade/lack of traceability’). The majority of the priority challenges, however, were associated with a deficient knowledge or training at farm level (‘poor business management training’, ‘lack of professionalization’, ‘slow adoption of innovations’), academia (‘researchers do not address real problems’) and society as a whole (‘low consumer education in local products’, ‘low social knowledge about farming’, ‘poor recognition of farming public services’). Thus, improved collaboration among the different stakeholders across the food chain with special implication of farmers, associations of producers, academia and governments is needed to facilitate knowledge exchange and capacity building. These actions can contribute to make ESRS economically more sustainable and to adapt the production systems and policy to the current and future societal needs in a more region-contextualized framework

    Bounded Representations of Interval and Proper Interval Graphs

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    Klavik et al. [arXiv:1207.6960] recently introduced a generalization of recognition called the bounded representation problem which we study for the classes of interval and proper interval graphs. The input gives a graph G and in addition for each vertex v two intervals L_v and R_v called bounds. We ask whether there exists a bounded representation in which each interval I_v has its left endpoint in L_v and its right endpoint in R_v. We show that the problem can be solved in linear time for interval graphs and in quadratic time for proper interval graphs. Robert's Theorem states that the classes of proper interval graphs and unit interval graphs are equal. Surprisingly the bounded representation problem is polynomially solvable for proper interval graphs and NP-complete for unit interval graphs [Klav\'{\i}k et al., arxiv:1207.6960]. So unless P = NP, the proper and unit interval representations behave very differently. The bounded representation problem belongs to a wider class of restricted representation problems. These problems are generalizations of the well-understood recognition problem, and they ask whether there exists a representation of G satisfying some additional constraints. The bounded representation problems generalize many of these problems

    First evidence of industrial fly-ash in an Antarctic ice core

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    Spheroidal carbonaceous particles (SCPs) are a component of fly-ash, the particulate by-product of industrial high temperature combustion of fuel-oil and coal-series fuels. We provide the first evidence that these indelible markers of industrialisation have been deposited in Antarctic ice, thousands of kilometres from any potential source. The earliest observed particle was deposited in an ice layer from 1936 CE. While depositional fluxes are low, chemical analysis of individual SCPs indicates a coal combustion origin

    Compton Scattering on the Deuteron in Baryon Chiral Perturbation Theory

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    Compton scattering on the deuteron is studied in the framework of baryon chiral perturbation theory to third order in small momenta, for photon energies of order the pion mass. The scattering amplitude is a sum of one- and two-nucleon mechanisms with no undetermined parameters. Our results are in good agreement with existing experimental data, and a prediction is made for higher-energy data being analyzed at SAL.Comment: 39 pages LaTeX, 19 figures (uses epsf

    Boost operators in Coulomb-gauge QCD: the pion form factor and Fock expansions in phi radiative decays

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    In this article we rederive the Boost operators in Coulomb-Gauge Yang-Mills theory employing the path-integral formalism and write down the complete operators for QCD. We immediately apply them to note that what are usually called the pion square, quartic... charge radii, defined from derivatives of the pion form factor at zero squared momentum transfer, are completely blurred out by relativistic and interaction corrections, so that it is not clear at all how to interpret these quantities in terms of the pion charge distribution. The form factor therefore measures matrix elements of powers of the QCD boost and Moeller operators, weighted by the charge density in the target's rest frame. In addition we remark that the decomposition of the eta' wavefunction in quarkonium, gluonium, ... components attempted by the KLOE collaboration combining data from phi radiative decays, requires corrections due to the velocity of the final state meson recoiling against a photon. This will be especially important if such decompositions are to be attempted with data from J/psi decays.Comment: 14 pages, 4 figure

    Compton scattering on the proton, neutron, and deuteron in chiral perturbation theory to O(Q^4)

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    We study Compton scattering in systems with A=1 and 2 using chiral perturbation theory up to fourth order. For the proton we fit the two undetermined parameters in the O(Q^4) γ\gammap amplitude of McGovern to experimental data in the region ω,∣t∣≤180\omega,\sqrt{|t|} \leq 180 MeV, obtaining a chi^2/d.o.f. of 133/113. This yields a model-independent extraction of proton polarizabilities based solely on low-energy data: alpha_p=12.1 +/- 1.1 (stat.) +/- 0.5 (theory) and beta_p=3.4 +/- 1.1 (stat.) +/- 0.1 (theory), both in units of 10^{-4} fm^3. We also compute Compton scattering on deuterium to O(Q^4). The γ\gammad amplitude is a sum of one- and two-nucleon mechanisms, and contains two undetermined parameters, which are related to the isoscalar nucleon polarizabilities. We fit data points from three recent γ\gammad scattering experiments with a chi^2/d.o.f.=26.6/20, and find alpha_N=13.0 +/- 1.9 (stat.) +3.9/-1.5 (theory) and a beta_N that is consistent with zero within sizeable error bars.Comment: 57 pages, 16 figures. Substantial changes. Correction of errors in deuteron calculation results in different values for isoscalar polarizabilities. Results for the proton are unaffected. Text modified to reflect this change, and also to clarify various point

    Helicity Analysis of Semileptonic Hyperon Decays Including Lepton Mass Effects

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    Using the helicity method we derive complete formulas for the joint angular decay distributions occurring in semileptonic hyperon decays including lepton mass and polarization effects. Compared to the traditional covariant calculation the helicity method allows one to organize the calculation of the angular decay distributions in a very compact and efficient way. In the helicity method the angular analysis is of cascade type, i.e. each decay in the decay chain is analyzed in the respective rest system of that particle. Such an approach is ideally suited as input for a Monte Carlo event generation program. As a specific example we take the decay Ξ0→Σ++l−+νˉl\Xi^0 \to \Sigma^+ + l^- + \bar{\nu}_l (l−=e−,μ−l^-=e^-, \mu^-) followed by the nonleptonic decay Σ+→p+π0\Sigma^+ \to p + \pi^0 for which we show a few examples of decay distributions which are generated from a Monte Carlo program based on the formulas presented in this paper. All the results of this paper are also applicable to the semileptonic and nonleptonic decays of ground state charm and bottom baryons, and to the decays of the top quark.Comment: Published version. 40 pages, 11 figures included in the text. Typos corrected, comments added, references added and update
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